Sorry if this has already been used but.... Could you use liquid Gallium as the coolant for calorimetry or does it react with metals you might use for pipework? Melting point about 30C, boiling point about 2400C. Would need a heated cabinet to pre-warm the system before turning on pumps or perhaps use the alloy Galinstan which is liquid at room temperature? Just thinking aloud.
PS: I agree an exact replication should be done first.